License compatibility
The need for such a framework arises because the different licenses can contain contradictory requirements, rendering it impossible to legally combine source code from separately-licensed software in order to create and publish a new program.
[1][2][failed verification] Proprietary licenses are generally program-specific and incompatible; authors must negotiate to combine code.
[emphasis added]A combined work consists of multiple differently-licensed parts (avoiding relicensing).
This can be achieved by separating the programs by an own process and allowing communication only via binary ABIs or other indirect means.
(ii) a license that permits the licensee to freely copy, modify and redistribute the Modified Version using the same licensing terms that apply to the copy that the licensee received, and requires that the Source form of the Modified Version, and of any works derived from it, be made freely available in that license fees are prohibited but Distributor Fees are allowed.
[citation needed] Therefore, the Debian project decided, in a 2006 resolution, to license documentation under the GPL.
[41] Despite that both are free software under a copyleft license, ZFS is not distributed with most linux distros like Debian[42][43] (but is distributed with FreeBSD) as the CDDL is considered incompatible with the GPL'ed Linux kernel, by the Free Software Foundation and some parties with relations with the FSF.
[45] In 2015, the CDDL to GPL compatibility question reemerged when the linux distribution Ubuntu announced that it would include OpenZFS by default.
Bottomley argued "a convincing theory of harm" cannot be developed, making it impossible to bring the case to court.
[48][self-published source] Eben Moglen, co-author of the GPLv3 and founder of the SFLC, argued that while the letters of the GPL might be violated the spirit of both licenses is adhered to, which would be the relevant issue in court.
[49] On the other hand, Bradley M. Kuhn and Karen M. Sandler, from the Software Freedom Conservancy, argued that Ubuntu would violate both licenses, as a binary ZFS module would be a derivative work of the Linux kernel, and announced their intent to achieve clarity in this question, even by going to court.
Re-licensing is achieved by contacting all involved developers and other parties and getting their agreement for the changed license.
Others in the FOSS domain, such as Eric S. Raymond, came to different conclusions regarding the requirements for re-licensing of an entire code base.
[61][62] Around 2001 Time Warner, exercising its rights under the Netscape Public License, and at the request of the Mozilla Foundation, re-licensed[63] all code in Mozilla that was under the Netscape Public License (including code by other contributors) to an MPL 1.1/GPL 2.0/LGPL 2.1 tri-license, thus achieving GPL-compatibility.
[68][69] In July 2013, the software re-licensed under the Mozilla Public License, the VLC application would then be resubmitted to the iOS App Store.
Therefore, at the request of the Wikimedia Foundation, the FSF added a time-limited section, to version 1.3 of the GFDL, that allowed specific types of websites using the GFDL to additionally offer their work under the CC BY-SA license.
[39][73] Another interesting case was Google's re-licensing of GPLv2-licensed Linux kernel header files to the BSD license for their Android library Bionic.
Google claimed that the header files were clean of any copyright-able work, reducing them to non-copyrightable "facts", and thus not covered by the GPL.
